Table 1. Efflux pump inhibitory activity and antimicrobial activity of flavonoids.
| Flavonoid | IC50 for efflux inhibition a | MIC b |
|---|---|---|
| Apigenin | 38 μg/mL (140 μM) | >150 μg/mL (>560 μM) |
| Kaempferol | 19 μg/mL (66.0 μM) | >150 μg/mL (>520 μM) |
| Rhamnetin | 19 μg/mL (60.0 μM) | >150 μg/mL (>470 μM) |
| Quercetin | 75 μg/mL (250 μM) | >150 μg/mL (>500 μM) |
| Luteolin | 75 μg/mL (260 μM) | 75 μg/mL (260 μM) |
| Myricetin | 75 μg/mL (240 μM) | 150 μg/mL (470 μM) |
| CCCP c | 4.7 μg/mL (23 μM) | 0.29 μg/mL (1.4 μM) |
a: Efflux pump inhibition was measured via LC-MS analysis of ethidium in spent, filtered culture supernatant after a 30 min incubation in triplicate wells.
b: Growth inhibition was measured by optical density at 600nm (in triplicate) after an 18 hr incubation.
c: CCCP is an abbreviation for the compound carbonyl cyanide m-chloro-phenylhydrazone